What is the ionosphere?
A) a layer of the atmosphere that is above the exosphere
B) a layer of the atmosphere characterized by the presence of ozone
C) a portion of the thermosphere in which the gas is ionized
D) a portion of the troposphere in which ions are common
C) a portion of the thermosphere in which the gas is ionized
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Falling stars and shooting stars are simply other names for meteors
Indicate whether the statement is true or false
Why is the nucleosynthesis era so important in determining the chemical composition of the universe?
A) We can study the processes that occurred during the nucleosynthesis era to determine how most of the elements in the universe were created. B) By knowing how much matter was created during the nucleosynthesis era, we can determine whether the universe is open or closed. C) We can observe spectra from this era to determine what the primordial mix of the elements was at the beginning of the universe. D) All the elements except hydrogen were produced in the nucleosynthesis era. E) Except for a small amount of elements heavier than helium produced later by stars, the chemical composition of the universe is the same now as at the end of the nucleosynthesis era.
In a supersaturated solution,
a. the solvent has become the solute. b. the normal solubility is exceeded. c. more solute than solvent is present. d. the dissolved and undissolved solute are in equilibrium.
Two wires A and B with circular cross sections are made of the same metal and have equal lengths, but the resistance of wire A is three times greater than that of wire B. What is the ratio of the radius of A to that of B?
1.3 2.?3 3.1 4.1/?3 5.1/3